Rate enhanced pulsed DC sputtering system

ABSTRACT

A pulsed direct current sputtering system and method are disclosed. The system has a plasma chamber with two targets, two magnetrons and one anode, a first power source, and a second power source. The first power source is coupled to the first magnetron and the anode, and provides a cyclic first-power-source voltage with a positive potential and a negative potential during each cycle between the anode and the first magnetron. The second power source is coupled to the second magnetron and the anode, and provides a cyclic second-power-source voltage. The controller phase-synchronizes and controls the first-power-source voltage and second-power-source voltage to apply a combined anode voltage, and phase-synchronizes a first magnetron voltage with a second magnetron voltage, wherein the combined anode voltage applied to the anode has a magnitude of at least 80 percent of a magnitude of a sum of the first magnetron voltage and the second magnetron voltage.

BACKGROUND

Field

The present invention relates generally to sputtering systems, and morespecifically to pulsed DC sputtering.

Background

Sputtering historically includes generating a magnetic field in a vacuumchamber and causing a plasma beam in the chamber to strike a sacrificialtarget, thereby causing the target to sputter (eject) material, which isthen deposited as a thin film layer on a substrate, sometimes afterreacting with a process gas. Sputtering sources may employ magnetronsthat utilize strong electric and magnetic fields to confine chargedplasma particles close to the surface of the target. An anode isgenerally provided to collect electrons from the plasma to maintainplasma neutrality as ions leave to bombard the target.

The industry has evolved over the years in various attempts to maximizesputtering efficiency, decrease power consumption requirements, minimizethe heat load of the system, minimize arcing and/or increase the typesof substrates that may be used in the system.

Moreover, sputtering a thin film of, for example, titanium dioxide(TiO₂) or silicon dioxide (SiO₂) onto a polyethylene substrate presentsunique challenges in the industry because polyethylene is a plastic witha low melting point or low heat tolerance. Currently-availablesputtering systems, whether DC or AC type systems, require a high heatload to effectuate sputtering and/or the deposition of TiO₂ or SiO₂, yetthis high heat load, caused by a high current density, effectivelyeliminates polyethylene as a suitable substrate for many intended highpower applications. Compounding the problem, if the heat load in thecurrently-available sputtering systems is lowered to a level that doesnot melt or otherwise render the polyethylene unsuitable, e.g., byreducing the power applied, the deposition rate is lowered to a pointthat results in a low-quality deposited layer and/or increases therequired time for sputtering to a point that renders the use ofpolyethylene as a substrate infeasible from a commercial perspective.

There therefore remains a need for a device that provides improvedsputtering deposition rates at a lower heat load.

SUMMARY

Embodiments disclosed herein address the above stated needs by providinga system, method, or non-transitory memory having instructions forpulsed direct current sputtering.

In some aspects, a pulsed direct current sputtering system is provided.The system may have a plasma chamber enclosing a first magnetron coupledto a first target, a second magnetron coupled to a second target, and ananode. A first power source may be coupled to the first magnetron andthe anode, and configured to provide a cyclic first-power-source voltagewith a positive potential and a negative potential during each cyclebetween the anode and the first magnetron. A second power source may becoupled to the second magnetron and the anode, and configured to providea cyclic second-power-source voltage with a positive potential and anegative potential during each cycle between the anode and the secondmagnetron. A controller may phase-synchronize and control a duty of thefirst-power-source voltage and second-power-source voltage to apply abipolar anode voltage to the anode that is a combination of the cyclicfirst-power-source voltage and the cyclic second-power source voltage.The controller may phase-synchronize a first magnetron voltage with asecond magnetron voltage. The combined anode voltage applied to theanode may have a magnitude of at least 80 percent of a magnitude of asum of the first magnetron voltage and second magnetron voltage.

In some aspects, a non-transitory memory including non-transitoryinstructions is provided. The non-transitory instructions are at leastone of executable by a processor to execute a method and accessible by afield programmable gate array to configure the field programmable gatearray to execute the method. The method may include causing a firstpower source to apply a first sputtering power having a first voltageand a first current to a first magnetron in a plasma chamber for a firstperiod of time, and causing a second power source to apply a secondsputtering power having a second voltage and a second current to asecond magnetron in the plasma chamber for the first period of time,with the first voltage and the second voltage providing a summedsputtering voltage. The method may also include causing the first powersource to apply a first anode power to an anode in the plasma chamberfor a second period of time following the first period of time, andcausing the second power source to apply a second anode power to theanode for the second period of time, with the first anode power and thesecond anode power providing a combined anode power having a combinedvoltage and a combined current. The combined voltage may have amagnitude of at least 80 percent of a magnitude of the summed sputteringvoltage. The first period of time may be at least 70 percent of asputtering cycle comprised of the first period of time and the secondperiod of time.

In some aspects, a method of pulsed direct current sputtering isprovided. The method may include providing a plasma chamber enclosing afirst magnetron coupled to a first target, a second magnetron coupled toa second target, and an anode, a first power source coupled to the firstmagnetron and the anode, a second power source coupled to the secondmagnetron and the anode, and a controller configured to control thefirst power source and the second power source to execute a method. Themethod may include causing the first power source to apply a firstsputtering power having a first voltage and a first current to the firstmagnetron for a first period of time, and causing the second powersource to apply a second sputtering power having a second voltage and asecond current to the second magnetron for the first period of time, thefirst voltage and the second voltage providing a summed sputteringvoltage. The method may also include causing the first power source toapply a first anode power to the anode for a second period of timefollowing the first period of time, and causing the second power sourceto apply a second anode power to the anode for the second period oftime, the first anode power and the second anode power providing acombined anode power having a combined voltage and a combined current.The combined voltage may have a magnitude of at least 80 percent of amagnitude of the summed sputtering voltage. The first period of time maybe at least 70 percent of a sputtering cycle comprised of the firstperiod of time and the second period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating some aspects of a sputteringsystem;

FIG. 2 is a graph of some aspects of power applications in a sputteringsystem;

FIG. 3 is a block diagram illustrating aspects of some hardwarecomponents that may be implemented in the system illustrated in FIG. 1;

FIG. 4 is a flowchart of a method disclosed herein;

FIG. 5 is a graphical depiction of power supplied by an exemplarysystem;

FIG. 6 is a graphical depiction of heat load test results of exemplarysystems described herein, compared to traditional AC systems;

FIG. 7 is a graphical depiction of a heat load resulting from the use ofa system described herein at 4 kW, compared to a traditional AC systemat 4 kW;

FIG. 8 is a graphical depiction of a heat load resulting from the use ofa system described herein at 4 kW, compared to a traditional AC systemat 8 kW; and

FIG. 9 is a graphical depiction of film thickness or deposition ratesachieved using various settings of an exemplary system disclosed herein,compared to various traditional AC systems.

DETAILED DESCRIPTION

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. For example, when power is appliedto the first and second magnetrons 104, 106, the power sources 140, 142will generate a current and a voltage with a first polarity, and whenpower is applied to the anode 108, the power sources 140, 142 willgenerate a current and a voltage with a second polarity that is reversedto the first polarity. A “power cycle” is intended to reference a timeperiod including a time of power having a voltage with the firstpolarity followed a time of power having a voltage with the secondpolarity. Further, for the purpose of this disclosure, all terms, andparticularly terms such as “simultaneously” and “equal to” are intendedto mean “within the tolerances of process or manufacturing controls”.For example, it will be understood that a synchronizing unit, such asunit 120, may not achieve perfect synchronization between the powersources 140, 142, and therefore the term “simultaneous(ly)” is to beunderstood as meaning “substantially simultaneous(ly)”.

Turning now to FIG. 1, an exemplary pulsed direct current sputteringsystem 100 is now described in detail. Generally stated, the system 100provides a user with the ability to achieve higher deposition rates, ascompared to prior AC dual magnetron and pulsed DC single magnetronsputtering approaches, by delivering higher power at a particularcurrent. More specifically, at a particular power level, someembodiments of the system 100 disclosed herein may cut the RMS currentin the endblocks or magnetrons by about half, as compared to prior ACsputtering systems. As a consequence, in cases in which the endblockcurrent rating is limited, the system 100 as disclosed may enabledelivery of nearly twice the power while staying within the endblockcurrent rating limit.

In a more specific example, the system 100 may be used by web coaters,who have in the past struggled with maintaining the sputtering processat manageable temperatures throughout production runs of over 7 days, toimprove deposition rates and quality. In currently-available systems,web coaters apply ventilation to the plasma chamber 101 to reduce theheat, which increases the production rate by 35% as compared to systemswithout ventilation. The system 100 presently disclosed provides, incontrast, a doubling of the production rate before cooling is evenapplied. That is, the system 100 and/or method 400 disclosed herein maylower the heat load or heating experienced by a substrate, even underapplication of the same power, and may be practiced to apply ahigh-quality layer of material, such as silicon dioxide (SiO₂) ortitanium dioxide (TiO₂), onto a polyethylene substrate, withoutdestroying the polyethylene substrate, and in a shortened period of timeas compared to those realized in currently-available systems. The SiO₂or TiO₂ layer may be thicker than what may be realized incurrently-available designs.

The system 100 may provide about 1.5 times the deposition rate of DCsingle magnetron or pulsed DC single magnetron sputtering, and about 2times the deposition rate of AC dual magnetron or bi-polar pulsed DCsputtering, with half the heat load experienced in thecurrently-available sputtering systems. The system 100 may include aplasma chamber 101 enclosing a first magnetron 102 engaged with a firsttarget 103, a second magnetron 104 engaged with a second target 105, andan anode 108. The system 100 may include a substrate 122 upon which thesystem 100 is to deposit a thin film material in a sputtering process.

A first bi-polar controllable pulsed DC power supply 112 (or firstbi-polar DC supply 112) and a second bi-polar controllable pulsed DCpower supply 114 (or second bi-polar DC supply 114) may be provided. Thefirst and second bipolar DC supplies 112, 114 may receive direct powerfrom a first direct current (DC) supply 116 and a second DC supply 118respectively. The first bi-polar DC supply 112 may be coupled to thefirst magnetron 102 by way of power lead(s) 124, and configured to applya sputtering power to the first target 103. Similarly, the secondbi-polar DC supply 114 may be coupled to the second magnetron 104, andconfigured to apply a sputtering power to the second target 105. Thefirst and second bi-polar DC supplies 112, 114 may be coupled to theanode 108 by way of lead(s) 128, and, more specifically, an electricaljoint 129 may couple a first anode lead 113 from the first bi-polar DCsupply 112 to a second anode lead 115 from the second bi-polar DC supply114. That is, the first power source 140 may be operatively coupled tothe anode 108 and the first target 103 by way of the first magnetron 102through leads 124, 113, and 128, while the second power source 142 maybe operatively coupled to the anode 108 and the second target 105 by wayof the second magnetron 104 through leads 126, 115, and 128.

In some embodiments, the anode may be the wall of the plasma chamber101; however, in others and as illustrated, the anode 108 may be afloating anode 108, and may further have a gas inlet 107 and a pluralityof gas outlets 109 enabling the hollow cathode effect to aid in keepingthe outlets clean for a more stable operation. Those of skill in the artwill understand that, because the anode 108 is a part of the powersupply delivery circuit, gas entering at the inlet 107 has an increasechance of breaking its bonds. For example, oxygen gas O₂ is more likelyto break into two oxygen atoms as the gas exits the plurality of outlets109, while nitrogen gas N₂ is more likely to break into two nitrogenatoms as it exits the plurality of outlets 109, resulting in films onthe substrate 122 that are of higher quality than would be expectedwithout the use of an anode 108 that provides a hollow cathode effect.

Some embodiments provide a system 100 that maintains an anode that doesnot “disappear” as is known in the industry, and in the system disclosedherein, the anode 108 may be kept clean or cleansed through operation athigher temperatures, by hollow cathode discharge in the plurality ofoutlets 109, and/or by sputtering directly during an application ofanode power.

In some embodiments, the system 100 maintains the anode 108, which maybe a floating gas anode, at a relatively high temperature suitable formaintaining a clean anode, while not causing the heat load within thechamber 101 and/or experienced by the substrate 122 to become so high asto damage the substrate 122, such as a polyethylene substrate, therein.In some embodiments, the system 100 may maintain the anode 108 at 100°Celsius, or more. In some embodiments, the system 100 may maintain theanode 108 at a temperature of about 150° Celsius. In some embodiments,the system 100 may maintain the anode 108 at 150° Celsius or less, suchas when in use by web coaters depositing titanium dioxide (TiO₂) orsilicon dioxide (SiO₂) onto a polyethylene substrate. In someembodiments, the system 100 may maintain the anode 108 at 200° Celsiusor more, such as when in use by glass coaters.

Continuing with FIG. 1, a controller 144 comprising a synchronizing unit120 may synchronize power signals from the first and second bi-polar DCsupplies 112, 114 in a manner that will be described in later portionsof this document. In some embodiments, a first power source 140 maycomprise the first bi-polar controllable pulsed DC power supply 112 andthe first DC supply 116. Similarly, a second power source may comprisethe second bi-polar controllable pulsed DC power supply 114 and thesecond DC supply 118.

Of note, each of the first and second power supplies 140, 142 may bearranged and configured to be aware of the other one of the first andsecond power supplies 140, 142, without attempting to control theoperation of the other one of the first and second power supplies 140,142. Applicant has achieved this “awareness without control” by firstconfiguring a duty cycle (e.g. 40 kHz) of each of the first and secondbi-polar DC supplies 112, 114, and subsequently coupling thesynchronizing unit 120 and configuring one of the first and secondbi-polar DC supplies 112, 114 to be perceived as a transmitter for thepurpose of frequency synchronization, and the other one of the first andsecond bi-polar DC supplies 112, 114 to be perceived as a receiver, forthe purpose of frequency synchronization. In contrast, each one of thefirst and second DC supplies 116, 118 are independent, and do not relyon awareness of the other one of the first and second DC supplies 116,118 to properly function.

Although not required, in one implementation, the first and second DCsupplies 116, 118 may each be realized by one or more ASCENT directcurrent power supplies sold by Advanced Energy Industries, Inc. of FortCollins, Colo., U.S.A. And the first and second bi-polar DC supplies112, 114 may each be realized by an ASCENT DMS Dual-magnetron sputteringaccessory, which is also sold by Advanced Energy Industries, Inc. ofFort Collins, Colo., U.S.A. In this implementation, the first and secondpower sources 140, 142 are each realized as an AMS/DMS stack wherein theASCENT direct current power supply may provide straight DC power andperform arc management functions, and the DMS dual-magnetron sputteringaccessory generates a pulsed DC waveform from the straight DC power.Beneficially, the DMS dual-magnetron sputtering accessories may belocated in close proximity to the chamber 101, and the ASCENT directcurrent power supplies may be located remotely (e.g., in a remote rack)from the chamber 101. The 120 synchronizing unit in this implementationmay be realized by a common exciter (CEX) function of the DMSaccessories.

In another embodiment, each of the first and second power sources 140,142 may be realized by an integrated pulsed DC power supply.

Turning now to FIG. 2, in some embodiments, the controller 144 and/orsynchronizing unit 120 may be configured to cause the first and secondbi-polar DC supplies 112, 114 or first and second power sources 140, 142to simultaneously apply sputtering power to the first and secondmagnetrons 104, 106, respectively, followed by a simultaneous anodepower to the anode 108.

In some embodiments, a cycle of power may be applied to the magnetrons102, 104 and the anode 108. As illustrated in FIG. 2 the synchronizingunit 120 may be configured to cause the first and second bi-polar DCsupplies 112, 114 to apply power to the magnetrons 104, 106 for a firstperiod of time t₁, followed by an application of power to the anode 108for a second period of time t₂, wherein the first period of time t₁ is80% of a sputtering cycle comprising the first and second periods oftime t₁, t₂. The second period of time t₂ may be about 20% of the cycle.In some embodiments, the first period of time t₁ may be at least 70% ofthe cycle, or, in some embodiments, between 70% and 90% of the cycle.The second period of time t₂ may be less than 30% of the cycle, orbetween 30% and 10% of the cycle. In some embodiments, the first periodof time t₁ may be between 80% and 90% of the cycle, and the secondperiod of time t₂ may be between 20% and 10% of the cycle. In someembodiments, the first period of time t₁ may be between 85% and 90% ofthe cycle, and the second period of time t₂ may be between 15% and 10%of the cycle.

As discussed further herein, the controller 144 may be configured tocontrol the first power source 140 and the second power source 142, andmay have a non-transitory memory including non-transitory instructionsto effectuate the methodologies described herein. For example, thenon-transitory instructions may be accessible by a field programmablegate array to configure the field programmable gate array to execute oneor more methods. In some embodiments, the non-transitory instructionsare executable by a processor and/or accessible by the fieldprogrammable gate array to configure the field programmable gate arrayto execute one or more methods. In other embodiments, one or moreaspects of the controller 144 may be realized by hardware (e.g.,application specific integrated circuits) that is persistentlyconfigured to control the first and second power sources 140, 142 toeffectuate one or more of the methods described herein.

Turning now to FIG. 2, certain novel and innovative aspects of asputtering process that may be executed by the system 100 are describedin detail. As illustrated in FIG. 2, the system 100 may be configured toapply a first power having a first voltage V₁ to the first magnetron 102for a first period of time t₁. Simultaneously, or for the first periodof time t₁, the system 100 may apply a second power having a secondvoltage V₂ to the second magnetron 104. In some embodiments, a magnitudeof the first voltage V₁ may be substantially the same as a magnitude ofthe second voltage V₂, although it will be understood that the valuesare highly idealized, and may not be perfectly matched in practice. Thesimultaneous application of the first power and the second power mayresult in an arbitrary summed voltage V_(sum) in a sputtering powerapplied for the first period of time t₁. That is, the term “summedvoltage V_(sum)” is not intended to mean that the system as a wholeexperiences a summed voltage, but rather that the first magnetron 102may experience a voltage and the second magnetron 104 may experience avoltage, with the voltage being summed for the purpose of analysis.

Continuing with FIG. 2, the first period of time t₁ may be followed by asecond period of time t₂. During the second period of time t₂, thesystem 100 may be configured to cause the first power source 140 toapply an anode power having a third voltage V₃ to the anode 108 and tosubstantially simultaneously cause the second power source 142 to applyan anode power having a fourth voltage V₄ to the anode 108. That is, thethird voltage V₃ and the fourth voltage V₄ may be combined to apply acombined power having a combined voltage V_(combined) to the anode 108for the second period of time t₂, because the third anode voltage V₃ andthe fourth anode voltage V₄ are applied together at the anode 108. Ofnote, when the two power sources 140, 142 apply power to the anode 108simultaneously, the anode current is additive; however, the resultingcombined voltage V_(combined) may not necessarily be, and generally isnot, the sum of the third voltage V₃ and the fourth voltage V₄. Those ofskill in the art will understand that V₁, V₂, and V_(combined) are allaffected by the impedance within the chamber.

While the graphical depictions in FIG. 2 are highly idealized, anapproximation of the powers and voltages may be provided. In someembodiments, the first voltage V₁ may be between about 300 Volts andabout 800 Volts. In some embodiments, the first voltage V₁ may be atleast 400 Volts. A magnitude of the second voltage V₂ may besubstantially equal to a magnitude of the first voltage V₁. A root meansquare or RMS may be taken to evaluate the voltage.

It should also be noted that V₁ and V₂ may be respectively measuredrelative to the anode 108, while V_(combined) may be measured relativeto ground. With brief reference to FIG. 5, for example, shown is anoscilloscope illustrating a top trace representing the voltage of theanode, or V_(combined), relative to ground, while the bottom traceillustrates a voltage applied to a first magnetron 102 relative to theanode 108. In some embodiments, V_(combined) is at least 70% of V_(sum).In some embodiments, V_(combined) is at least 80% of V_(sum).

The methods described in connection with the embodiments disclosedherein may be embodied directly in hardware, in processor executableinstructions encoded in non-transitory processor readable medium, or ina combination of the two. Referring to FIG. 3 for example, shown is ablock diagram depicting physical components that may be utilized torealize the controller 144 according to an exemplary embodiment. Asshown, in this embodiment a display portion 312 and nonvolatile memory320 are coupled to a bus 322 that is also coupled to random accessmemory (“RAM”) 324, a processing portion (which includes N processingcomponents) 326, a field programmable gate array (FPGA) 327, and atransceiver component 328 that includes N transceivers. Although thecomponents depicted in FIG. 3 represent physical components, FIG. 3 isnot intended to be a detailed hardware diagram; thus many of thecomponents depicted in FIG. 3 may be realized by common constructs ordistributed among additional physical components. Moreover, it iscontemplated that other existing and yet-to-be developed physicalcomponents and architectures may be utilized to implement the functionalcomponents described with reference to FIG. 3.

This display portion 312 generally operates to provide a user interfacefor a user, and in several implementations, the display is realized by atouchscreen display. In general, the nonvolatile memory 320 isnon-transitory memory that functions to store (e.g., persistently store)data and processor executable code (including executable code that isassociated with effectuating the methods described herein). In someembodiments for example, the nonvolatile memory 320 includes bootloadercode, operating system code, file system code, and non-transitoryprocessor-executable code to facilitate the execution of a methoddescribed with reference to FIG. 4.

In many implementations, the nonvolatile memory 320 is realized by flashmemory (e.g., NAND or ONENAND memory), but it is contemplated that othermemory types may be utilized as well. Although it may be possible toexecute the code from the nonvolatile memory 320, the executable code inthe nonvolatile memory is typically loaded into RAM 324 and executed byone or more of the N processing components in the processing portion326.

The N processing components in connection with RAM 324 generally operateto execute the instructions stored in nonvolatile memory 320 to enablethe power sources 140, 142 to achieve one or more objectives. Forexample, non-transitory processor-executable instructions to effectuatethe methods described with reference to FIG. 4 may be persistentlystored in nonvolatile memory 320 and executed by the N processingcomponents in connection with RAM 324. As one of ordinary skill in theart will appreciate, the processing portion 326 may include a videoprocessor, digital signal processor (DSP), graphics processing unit(GPU), and other processing components.

In addition, or in the alternative, the FPGA 327 may be configured toeffectuate one or more aspects of the methodologies described herein(e.g., the method described with reference to FIG. 4). For example,non-transitory FPGA-configuration-instructions may be persistentlystored in nonvolatile memory 320 and accessed by the FPGA 327 (e.g.,during boot up) to configure the FPGA 327 to effectuate the functions ofthe controller 144.

The input component operates to receive signals that are indicative ofone or more aspects of the power applied to the first magnetron 102and/or the second magnetron 104. The signals received at the inputcomponent may include, for example, voltage, current, and/or power. Theoutput component generally operates to provide one or more analog ordigital signals to effectuate an operational aspect of the first and/orsecond power sources 140, 142. For example, the output portion may be asignal to cause the first power source and/or second power source 112,114 to effectuate some of the methodologies described with reference toFIG. 4. In some embodiments, the output component operates to adjust afrequency and duty of the first and/or second power source 140, 142.

The depicted transceiver component 328 includes N transceiver chains,which may be used for communicating with external devices via wirelessor wireline networks. Each of the N transceiver chains may represent atransceiver associated with a particular communication scheme (e.g.,WiFi, Ethernet, Profibus, etc.).

Turning now to FIG. 4, a method 400 of sputtering that may be executedby the system 100 in some embodiments is now described in more detail.The method 400 may include providing 402 a plasma chamber, a first powersource, a second power source, and other sputtering components.Providing 402 may be achieved by providing a system such as system 100described with reference to FIGS. 1-3. The method 400 may includecausing 404 the first power source to apply a first sputtering power tothe first magnetron for a first period of time. The method 400 may alsoinclude causing 406 the second power source to apply a second sputteringpower to the second magnetron for the first period of time, the firstsputtering power and the second sputtering power providing a summedsputtering voltage. In some embodiments, the method 400 may includecalculating 414 one or more of a summed sputtering power, a summedsputtering voltage, and a summed sputtering current applied to the firstmagnetron and the second magnetron.

The method 400 may also include causing 408 the first power source toapply a first anode power to the anode for a second period of timefollowing the first period of time. The method 400 may also includecausing 410 the second power source to apply a second anode power to theanode for the second period of time, the first anode power and thesecond anode power providing a combined anode power.

The method 400 may include combining 412 an anode power to the anodesuch that the combined anode power, having a current and a voltage, hasa voltage having a magnitude of at least 80% of a magnitude of thesummed sputtering voltage.

In method 400, the first period of time may be at least 80% of asputtering cycle, the sputtering cycle comprised of the first period oftime and the second period of time. In some embodiments, the firstperiod of time is at least 70% of the sputtering cycle. In someembodiments, the combined anode voltage has a magnitude of at least 800Volts. In some embodiments, the first period of time t₁ may be between70% and 90% of the cycle, and the second period of time t₂ may bebetween 30% and 10% of the cycle. In some embodiments, the first periodof time t₁ may be between 80% and 90% of the cycle, and the secondperiod of time t₂ may be between 20% and 10% of the cycle. In someembodiments, the first period of time t₁ may be between 85% and 90% ofthe cycle, and the second period of time t₂ may be between 15% and 10%of the cycle.

In some embodiments, the first sputtering power has a voltage having amagnitude of at least 300 Volts, and the second sputtering power has avoltage having a magnitude of at least 300 Volts.

In some embodiments, the combined anode power has a current and avoltage, the voltage having a magnitude of at least 1000 Volts.

In some embodiments, the anode is a floating anode comprising a gas barhaving a gas inlet and a plurality of gas outlets shaped to provide aHollow Cathode Effect.

In some embodiments, the method 400 includes causing a synchronizer tocause the first power source and the second power source tosimultaneously apply power to the first magnetron and the secondmagnetron for the first period of time and to cause the first powersource and the second power source to simultaneously apply power to theanode for the second period of time.

To determine basic functionality, the system 100 and method 400previously described herein were tested using TiO_(x) as the targetmaterial, 6.4 mTorr using 126 SCCM argon and 100 SCCM oxygen as thereactive gas, 4 kW of applied power per magnetron with a floating anodesitting between them, and a line speed of 10 inches per minute. Table 1illustrates the results of the functionality test, establishing that thesystem 100 would operate.

TABLE 1 Functionality Test Observations at first plasma. Item VoltageCurrent V1 (V of first magnetron 102 to anode −535 V 7.2 A 108) V2 (V ofsecond magnetron 104 to anode −565 V 7.1 A 108) Voltage of Anode 108 toGround   850 V NA Anode −680 V_(combined) 2.2 A Voltage of firstmagnetron 102 to Ground −720 V NA

The above functionality test verified that the system 100 was functionalsubstantially as envisioned, and was attempting to deliver full power tothe anode 108. Of note, an unforeseen result of the functionality testrevealed that the anode power exhibited a current of just 2.2 Amperes,or about half of what was expected.

Applicant has determined that, because there was no magnetic enhancementon the anode 108, it would take very high voltages to do any more workbeyond heating the anode 108, which was also found to be a desirableresponse. That is, V_(combined) is high enough to result in a very lowcurrent at the anode 108 in the functionality test. Moreover, becausethe current is additive, a current at the anode 108 of just 2.2 Amperesindicates than a current approaching 0 is experienced at each of thefirst and second magnetrons 102, 104—another desirable result to preventundesirable coating of the first and second magnetrons 102, 104 duringan anode power pulse.

Beyond the functionality test, the system was tested under three othersettings, described below under runs 1, 2, and 3. Benchmark runs 4 and 5were also performed using a traditional AC sputtering system asdescribed below. By measuring a film deposition thickness at the samegiven line speed, deposition rates could be calculated. The heat load ortemperature of the substrate 122 was also measured, as was the voltageand current at the magnetrons 102, 140 and anode 108. Of note, the setupwas run on a sputter-down machine with relatively small magnetrons, soprocess power was limited.

Turning now to FIG. 6, illustrating a summary of the heat loadresponses, a series of tests were performed at various frequencies,notably run 1 was at 20 kHz, run 2 was at 30 kHz, and run 3 was at 40kHz with as much Side A ON time as possible, that is, with as much timeof power application to the magnetrons.

To compare deposition rates and heat loads, the system 100 was comparedto a currently available Advanced Energy PEII AC power supply,illustrated at benchmark test runs 4 and 5.

With each run, a film thickness measurement was taken using a Dektak®profilometer, with a Sharpie® mark on the bare glass. Scrubbing thecoated glass over the Sharpie mark removes the coating so a goodthickness step could be obtained.

Also with each run, the heat load on the substrate was measured by aSuperMole, which is a circuit board encased by many heat shields with atype K thermocouple super-glued to the glass substrate. The SuperMoletook real-time temperature measurements through the plasma and theresults were then downloaded and stored.

With simultaneous reference now to FIGS. 6-9, the 5 runs were completed,with all machine setups maintained as described above. The results ofthe 5 runs are described below.

TABLE 2 Run 1. System 100 @ 4 kW, 20 kHz. DC Supply Settings PowerVoltage Current 1^(st) DC supply 116 Settings 4 kW V₁ = 513 V I₁ = 7.8 A2^(nd) DC supply 118 Settings 4 kW V₂ = 526 V I₂ = 7.7 A Side A SettingsFrequency Side A Side B Boost 1^(st) bi-polar DC supply 112 20 kHz 90%10% 50% 2^(nd) bi-polar DC supply 114 Side B (Anode 108) SettingsVoltage Current 1^(st) bi-polar DC supply 112 V₃ = 589 V I₃ = 2.8 A2^(nd) bi-polar DC supply 114 V₄ = 598 V I₄ = 3.4 A Anode V_(combined)not measured I_(combined) = 6.2 A

TABLE 3 Run 2. System 100 @ 4 kW, 30 kHz. DC Supply Settings PowerVoltage Current 1^(st) DC supply 116 Settings 4 kW V₁ = 527 V I₁ = 7.6 A2^(nd) DC supply 118 Settings 4 kW V₂ = 542 V I₂ = 7.4 A Side A SettingsFrequency Side A Side B Boost 1^(st) bi-polar DC supply 112 30 kHz 85%15% 50% 2^(nd) bi-polar DC supply 114 Side B (Anode 108) SettingsVoltage Current 1^(st) bi-polar DC supply 112 V₃ = 637 V I₃ = 2.2 A2^(nd) bi-polar DC supply 114 V₄ = 647 V I₄ = 2.2 A Anode V_(combined)not measured I_(combined) = 4.4 A

TABLE 4 Run 3. System 100 @ 4 kW, 40 kHz. DC Supply Settings PowerVoltage Current 1^(st) DC supply 116 Settings 4 kW V₁ = 545 V I₁ = 7.3 A2^(nd) DC supply 118 Settings 4 kW V₂ = 552 V I₁ = 7.2 A Side A SettingsFrequency Side A Side B Boost 1^(st) bi-polar DC supply 112 40 kHz 80%20% 50% 2^(nd) bi-polar DC supply 114 Side B (Anode 108) SettingsVoltage Current 1^(st) bi-polar DC supply 112 V₃ = 678 V I₃ = 2.2 A2^(nd) bi-polar DC supply 114 V₄ = 680 V I₄ = 2.2 A Anode V_(combined)not measured I_(combined) = 4.4 A

TABLE 5 Run 4. Traditional AC System @ 4 kW. PEII Settings Power VoltageCurrent PEII AC Power Settings 4 kW 570 V 7.6 A

TABLE 6 Run 5. Traditional AC System @ 8 kW. PEII Settings Power VoltageCurrent PEII AC Power Settings 8 kW 630 V 14 A

FIG. 7 illustrates the heat load results of the system 100 running at 40kHz and 4 kW, as compared to an AC system at 4 kW. FIG. 8 illustratesthe heat load results of the system 100 running at 40 kHz and 4 kW, ascompared to an AC system at 8 kW. FIG. 9 illustrates the resulting filmthickness for each of the 5 runs (runs 1-3 being test runs and runs 4-5being benchmark tests of AC systems).

With reference now to FIGS. 7 and 9, FIG. 7 indicates that the system100 results in less heating (under 300 degrees Celsius verses over 300degrees Celsius). Moreover, and with reference to tables 3 and 5, thesystem 100 provides a combined current Icombined of 4.4 Amperes at apower of 4 kW, while an AC system at 4 kW provides a current of 7.6Amperes. That is, at the same power wattage settings, the system 100causes the anode 108 to experience significantly less current (4.4Amperes verses 7.6 Amperes), resulting in a relatively hot anode,improving cleaning properties of the anode, and yet maintaining arelatively cool substrate. In light of FIG. 9, the system 100 at thesame power settings of a traditional AC system results in a muchimproved deposition rate (over 350 Angstroms verses about 225Angstroms), meaning that a processing facility may realize significantyields without damage to sensitive substrates, such as polyethylene.

With reference now to FIGS. 8 and 9, illustrating the system 100 withthe first and second bi-polar DC supplies 112, 114 operating at 40 kHz,and the first and second DC supplies 116, operating at 4 kW per side,compared to a traditional PEII AC system running at 8 kW, it is notedthat, although the traditional system resulted in a thicker film, thesystem 100 resulted in a much lower heat load. That is, although thedeposition rate was just slightly more with the traditional system, theheat load was half on the system 100 as herein described. While this isinteresting it is not where a usual process engineer would be when an ACpower or current limit is hit and more deposition rate is required. Forexample, if a sputtering zone is running at 90 kW and is hitting the 300amp AC current limit a traditional system, a system 100 is describedherein could be used instead. Placing two 120 kw power supplies 140, 142in place of a 120 kW AC delivery system would result in the dramaticdifferences illustrated in FIGS. 7 and 9. With a system 100 as hereindescribed, it is possible to push more power into the power-deliverysystem without breaching the inductive heating current limit. The system100 may improve production speeds, add deposition rates without addingcathode lids, use existing cathodes to their fullest extent, and keepsubstrates much cooler.

With reference to tables 3 and 6, one can see that the system 100provides a combined current I_(combined) of 4.4 Amperes at a power of 4kW, while an AC system at 8 kW provides a current of 14 Amperes. Takenin light of FIG. 9, one can see that the system 100 at 4 kW and 40 kHzresults in a deposition rate that approaches that of a traditional ACsystem at twice the power, but resulting in significantly less current(4.4 Amperes verses 14 Amperes) and a much lower heat load (about 300degrees Celsius verses over 500 degrees Celsius).

A close analysis of FIG. 9 reveals that using a first power supply 140and a second power supply 142 as previously described herein increasesthe deposition rates as compared to a traditional AC type sputteringsystem at the same power. For example, the system 100 running at 4 kWper side and 20 kHz results in a film thickness of 470 Angstroms, whilethe traditional PEII AC system at 4 kW results in a film thickness ofjust 230 Angstroms. To approach the deposition rates of the system 100,a traditional AC system would have to apply more than 8 kW of power.

Put succinctly, Applicant has provided a system, method, and means forincreasing the deposition rate while drastically reducing the heat loadexperienced by the substrate 122 at the same or lower power as that of atraditional AC system, and the current experienced by the anode 108 andmagnetrons 102, 104, which, as previously described, was an unexpectedresult.

Returning now to FIG. 6, one can deduce that system 100 may run at anynumber of frequencies, including 20, 30, and 40 kHz, or others andprovide a much better Angstrom/substrate temperature profileconsistently over traditional AC power delivery.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

The invention claimed is:
 1. A pulsed direct current sputtering system,comprising: a plasma chamber enclosing a first magnetron coupled to afirst target, a second magnetron coupled to a second target, and ananode; a first power source coupled to the first magnetron and theanode, the first power source configured to provide a cyclicfirst-power-source voltage with a positive potential and a negativepotential during each cycle between the anode and the first magnetron; asecond power source coupled to the second magnetron and the anode, thesecond power source configured to provide a cyclic second-power-sourcevoltage with a positive potential and a negative potential during eachcycle between the anode and the second magnetron; and a controllerconfigured to phase-synchronize and control a duty of thefirst-power-source voltage and second-power-source voltage to apply abipolar anode voltage to the anode that is a combination of the cyclicfirst-power-source voltage and the cyclic second-power source voltage,and to phase-synchronize a first magnetron voltage with a secondmagnetron voltage, wherein the combined anode voltage applied to theanode has a magnitude of at least 80 percent of a magnitude of a sum ofthe first magnetron voltage and second magnetron voltage; and whereinthe controller comprises a field programmable gate array, and anon-transitory memory including non-transitory instructions accessibleby the field programmable gate array to configure the field programmablegate array to: cause the first power source to apply a first sputteringpower having a first voltage and a first current to the first magnetronfor a first period of time; cause the second power source to apply asecond sputtering power having a second voltage and a second current tothe second magnetron for the first period of time; cause the first powersource to apply a first anode power to the anode for a second period oftime following the first period of time; and cause the second powersource to apply a second anode power to the anode for the second periodof time; and wherein the first anode power and the second anode powerresult in a combined anode power having a combined current that is lessthan each of the first current and the second current.
 2. The system ofclaim 1, wherein: the controller comprises a processor, and anon-transitory memory comprising non-transitory instructions executableby the processor to: cause the first power source to apply a firstsputtering power having a first voltage and a first current to the firstmagnetron for a first period of time; cause the second power source toapply a second sputtering power having a second voltage and a secondcurrent to the second magnetron for the first period of time; cause thefirst power source to apply a first anode power to the anode for asecond period of time following the first period of time; and cause thesecond power source to apply a second anode power to the anode for thesecond period of time; and wherein the first anode power and the secondanode power result in a combined anode power having a combined currentthat is less than each of the first current and the second current. 3.The system of claim 1, wherein: the first power source comprises a firstdirect current power supply coupled to a first bi-polar controllablepulsed direct current power supply, the first bi-polar controllablepulsed direct current power supply configured to provide an alternatingdirect current power to the first magnetron and the anode; and thesecond power source comprises a second direct current power supplycoupled to a second bi-polar controllable pulsed direct current powersupply, the second bi-polar controllable pulsed direct current powersupply configured to provide an alternating direct current power to thesecond magnetron and the anode.
 4. The system of claim 1 wherein: theanode is a floating anode.
 5. The system of claim 1, further comprising:a synchronizer configured to synchronize the first power source and thesecond power source, wherein the non-transitory instructions includeinstructions to cause the synchronizer to cause the first power sourceand the second power source to simultaneously apply power to the firstmagnetron and the second magnetron for the first period of time and tocause the first power source and the second power source tosimultaneously apply power to the anode for the second period of time.6. The system of claim 1, further comprising: a first electrical leadfor coupling the first power source and the first magnetron; a secondelectrical lead for coupling the second power source and the secondmagnetron; and a third electrical lead for coupling the first powersource, the second power source, and the anode such that an applicationof power by the first power source and the second power source resultsin the combined anode power application to the anode.
 7. The system ofclaim 1, further comprising: the first sputtering power to the firstmagnetron has a voltage having a polarity; and the second sputteringpower to the second magnetron has a voltage having the polarity; whereinthe controller is configured to cause the polarity to reverse toeffectuate an application of the first anode power for the second periodof time.
 8. A non-transitory memory including non-transitoryinstructions that are at least one of executable by a processor toexecute a method and accessible by a field programmable gate array toconfigure the field programmable gate array to execute the method, themethod comprising: causing a first power source to apply a firstsputtering power having a first voltage and a first current to a firstmagnetron in a plasma chamber for a first period of time; causing asecond power source to apply a second sputtering power having a secondvoltage and a second current to a second magnetron in the plasma chamberfor the first period of time, the first voltage and the second voltageproviding a summed sputtering voltage; causing the first power source toapply a first anode power to an anode in the plasma chamber for a secondperiod of time following the first period of time; causing the secondpower source to apply a second anode power to the anode for the secondperiod of time, the first anode power and the second anode powerproviding a combined anode power having a combined voltage and acombined current; wherein the combined voltage has a magnitude of atleast 80 percent of a magnitude of the summed sputtering voltage; andthe first period of time is at least 70 percent of a sputtering cycle,the sputtering cycle comprised of the first period of time and thesecond period of time.
 9. The non-transitory memory of claim 8, wherein:the first period of time is at least 85 percent of the sputtering cycle.10. The non-transitory memory of claim 8, wherein: the combined currentis less than each of the first current and the second current.
 11. Thenon-transitory memory of claim 10, wherein: the first voltage has amagnitude of at least 300 Volts; and the second voltage has a magnitudeof at least 300 Volts.
 12. The non-transitory memory of claim 10,wherein: the combined voltage has a magnitude of at least 1000 Volts.13. The non-transitory memory of claim 8, wherein: the anode is afloating anode.
 14. A method of pulsed direct current sputtering,comprising: providing a plasma chamber enclosing a first magnetroncoupled to a first target, a second magnetron coupled to a secondtarget, and an anode; a first power source coupled to the firstmagnetron and the anode; a second power source coupled to the secondmagnetron and the anode; and a controller configured to control thefirst power source and the second power source, the controllercomprising a non-transitory memory including non-transitory instructionsthat are at least one of executable by a processor to execute a methodand accessible by a field programmable gate array to configure the fieldprogrammable gate array to execute the method; the method comprising:causing the first power source to apply a first sputtering power havinga first voltage and a first current to the first magnetron for a firstperiod of time; causing the second power source to apply a secondsputtering power having a second voltage and a second current to thesecond magnetron for the first period of time, the first voltage and thesecond voltage providing a summed sputtering voltage; causing the firstpower source to apply a first anode power to the anode for a secondperiod of time following the first period of time; causing the secondpower source to apply a second anode power to the anode for the secondperiod of time, the first anode power and the second anode powerproviding a combined anode power having a combined voltage and acombined current; wherein the combined voltage has a magnitude of atleast 80 percent of a magnitude of the summed sputtering voltage; andthe first period of time is at least 70 percent of a sputtering cycle,the sputtering cycle comprised of the first period of time and thesecond period of time.
 15. The method of claim 14, wherein: the firstperiod of time is at least 85 percent of the sputtering cycle.
 16. Themethod of claim 14, wherein: the combined current is less than each ofthe first current and the second current.
 17. The method of claim 16,wherein: the first voltage has a magnitude of at least 300 Volts; andthe second voltage has a magnitude of at least 300 Volts.
 18. The methodof claim 14, wherein: the anode is a floating anode.
 19. The method ofclaim 14, comprising: causing the first power source and the secondpower source to simultaneously apply the first sputtering power to thefirst magnetron and the second sputtering power to the second magnetronfor the first period of time, the first sputtering power having avoltage having a polarity, and the second sputtering power having avoltage having the polarity, and to cause the first power source and thesecond power source to simultaneously reverse the polarity to apply theanode power to the anode for the second period of time.